CN102778552B - Experimental method for fracture reorientation rule in oriented perforating and fracturing process - Google Patents
Experimental method for fracture reorientation rule in oriented perforating and fracturing process Download PDFInfo
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- CN102778552B CN102778552B CN201210272304.4A CN201210272304A CN102778552B CN 102778552 B CN102778552 B CN 102778552B CN 201210272304 A CN201210272304 A CN 201210272304A CN 102778552 B CN102778552 B CN 102778552B
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Abstract
The invention provides an experimental method for researching the fracture reorientation in the oriented perforating and fracturing process. The experimental method comprises the following steps of: A, making a test piece by a core exposure cube of which the side edge is greater than or equal to 1m; B, then arranging the test piece in a three-axis stress loading device and sequentially carrying out oriented perforating and fracturing on the test piece under the three-axis stress loading condition; and C, after carrying out fracturing, analyzing the test piece. The experimental method provided by the invention has a more reliable test result and is convenient to observe a fracture extension rule.
Description
Technical field
The present invention relates to field of petroleum exploitation, in particular to hydraulic fracturing technology, turn to the method for rule for study of rocks oriented perforating and fracturing fracture under three-dimensional stress state, namely oriented perforating and fracturing fracture turn to the experimental technique of research.
Background technology
Current research oriented perforating and fracturing fracture turn to the key step of the experimental technique of research as follows: 1. cement specimen of casting (0.3m cube), bury iron pipe, paper roll in advance and replace pit shaft and perforation interval respectively before casting; 2. test specimen is put into loader, by three hydraulic jacks respectively three direction pressurizations, the three-dimensional stress under simulated formation state; 3. with high-pressure pump, high pressure injection is carried out to test specimen, press off test specimen and form crack; 4. observe the relation of perforation direction and fracture azimuth.This method mainly contains following limitation:
Can only test with cement casting, and under real core condition, carry out test differ greatly, impact test confidence level, in addition, fracturing parameter and field condition difference also larger;
Sample dimensions is less, and fracture propagation reaches border fast, is difficult to fully observe fracturing fracture steering procedure, is unfavorable for the research turning to rule.
Summary of the invention
The invention provides the experimental technique that a kind of oriented perforating and fracturing fracture turn to research, to solve existing experimental water mud casting test, and under real core condition, carry out test differ greatly, the problem of impact test confidence level.In addition, it is less that the present invention can also solve sample dimensions, and fracture propagation reaches border fast, is unfavorable for the problem of pressure break research.
For this reason, the present invention proposes the experimental technique that a kind of oriented perforating and fracturing fracture turn to research, described experimental technique comprises the following steps: A, the rock core adopting the length of side to be more than or equal to 1m cube of appearing makes test specimen, B, then described test specimen is arranged in triaxial stress charger, under the condition that triaxial stress loads, successively oriented perforating and pressure break are carried out to described test specimen, after C, pressure break, dissect described test specimen.
Further, the described rock core cubical length of side of appearing is 1.5 meters.
Further, described steps A comprises: to appear cubical end face central bore at described rock core, loads sleeve pipe, carries out well cementing of cement.
Further, described triaxial stress charger comprises: 6 that are formed by the casting support frames with square support face, pinned connection is adopted to fix between adjacent described support frame, 6 described support frames are formed and surround described rock cores and to appear cubical space, and described rock core cube of appearing is arranged in described space.
Further, 6 described support frames are respectively the support frame of the support frame of end face, the support frame of bottom surface and four sides, the support frame of described four sides comprises: the first side support frame and the second side support frame, first side support frame is positioned at the first side, second side support frame is positioned at the second side, and described first side is adjacent and crossing with described second side;
The support frame of described bottom surface, described first side support frame and the push pedal of the described test specimen of pushing described second side support frame being respectively equipped with lifting jack and be connected with described lifting jack; By from described bottom surface, described first side and these three directions, described second side load to realize triaxial stress respectively to the cube pressurization of appearing of described rock core.
Further, the lifting jack of the support frame of described bottom surface, described first side support frame and described second side support frame individually controls pressurization.
Further, enter hydraulic ejector under in sleeve pipe and realize oriented perforating and pressure break connection is done, in described step B, by under enter hydraulic ejector and realize oriented perforating.
Further, in described step B, carry out abrasive perforating 10 minutes to realize oriented perforating to described test specimen, close sleeve gate afterwards and carry out pressure break to described test specimen, pressure break adopts 2000 type Frac units 2 to 6 covers, pressure break discharge capacity 2.0m
3/ min.
In described step B, described triaxial stress is loaded as: the lifting jack that the lifting jack of the support frame of described bottom surface is pressurized to 50Mpa, the lifting jack of described first side support frame is pressurized to 25MPa and described second side support frame is pressurized to 40MPa.
Present invention employs rock core cube of appearing and carry out triaxial stress loading simulation oriented perforating as test specimen and fracturing fracture turns to development test, test specimen is identical with field condition, tests with a high credibility, can fully simulate and close to field condition.
And then the rock core that the present invention adopts the length of side to be more than or equal to 1m appears cube as test specimen, the process that fracture propagation reaches border is extended, and thus obtains the room and time fully observing fracturing fracture steering procedure, is conducive to the research turning to rule.
And then the present invention applies different pressure at three compression aspects, fully simulates actual geologic condition.
And then the employing of the present invention subsurface tool consistent with site operation, shaft structure, Frac unit, oriented perforating parameter carry out ground simulation test, and more close with mining site reality, experimental result more accurately and reliably.By conditions such as analog directional perforation, triaxial stress, mining site pressure breaks truly, demonstrating oriented perforating can force initial fracturing fracture to turn to, thus is formed and depart from and the crack of final parallel major principal stress.
Accompanying drawing explanation
Fig. 1 is the perspective view of the support frame of the bottom surface not with lifting jack according to the embodiment of the present invention;
Fig. 2 is the perspective view of the support frame of the bottom surface of band lifting jack according to the embodiment of the present invention;
Fig. 3 is the structural representation of the triaxial stress charger of the support frame assembling bottom surface, the first side support frame and the second side support frame according to the embodiment of the present invention;
In Fig. 4 Fig. 3, each support frame all installs the structural representation of lifting jack;
Fig. 5 is the structural representation that Fig. 3 assembles again the support frame of all the other two sides;
Fig. 6 is the structural representation that Fig. 5 assembles again the support frame of end face;
Fig. 7 is the structural representation that Fig. 6 has installed again the casing flange of test specimen;
Fig. 8 only retains the support frame of end face and the structural representation of test specimen in Fig. 6.
Drawing reference numeral illustrates:
1, support 2, push pedal 3, lifting jack 4, connect lug 5, connecting hole 10, support frame 20, first side support frame 30, second side support frame 40 of bottom surface, the support frame 50 of end face, the 3rd side support frame 60, the 4th side support frame 70, rock core appear cube 75, sleeve pipe 77, flange
Embodiment
In order to there be understanding clearly to technical characteristic of the present invention, object and effect, now contrast accompanying drawing and illustrate of the present invention
Embodiment.
The present invention proposes the experimental technique that a kind of oriented perforating and fracturing fracture turn to research, and described experimental technique comprises:
The rock core that adopts the length of side to be more than or equal to 1m cube of appearing makes test specimen as test specimen, then under the condition of three axles (orthogonal three axles or three directions) stress loading, successively carry out oriented perforating and pressure break, then described test specimen is dissected, the relation of research perforation direction and fracture azimuth.It is by collecting from mining site that rock core is appeared, and after adopting, cuts into cube, refacing, control surface precision.Rock core cube of appearing is more than or equal to 1m and mainly considers the radius that fracturing fracture turns to and distance, and usually, the radius that fracturing fracture turns to and distance, more than 0.5 meter, if test specimen is too little, are then difficult to effectively be observed and data.
Certainly, from the angle that research is observed, rock core is appeared and is the bigger the better, close to the geologic condition of reality, but as fruit volume is excessive, then need very large pressure and device to exert a force to test specimen, to simulate the stress under triaxial stress, this can increase the complicacy of device and construction and the difficulty of force, the stress under likely making test specimen can not reach actual geologic condition.Preferably, the described rock core cubical length of side of appearing is 1.5 meters, like this, has taken into account research and has observed and construction two aspects.
Further, make test specimen and comprise: to appear cubical end face central bore at described rock core, load sleeve pipe, carry out well cementing of cement, to reach the shaft structure consistent with site operation.
Further, described triaxial stress charger comprises: 6 that are formed by the casting support frames with square support face, pinned connection is adopted to fix between adjacent described support frame, 6 described support frames are formed and surround described rock cores and to appear cubical space, and described rock core cube of appearing is arranged in described space.Like this, rock core to be appeared firm being fixed up of cube by support frame, carry out triaxial stress loading with cube of appearing to rock core.Support frame has been clamping and the platy structure of supporting role or supporting structure or framed structure, and support frame is played a supporting role on the one hand, for lifting jack provides support, allows the hydraulic line of lifting jack to pass on the other hand, pressurizes from the face of push pedal.Support frame is made up of casting, is not afraid of colliding with in experimentation, and wear-resistant, load-bearing capacity is strong.
Further, as shown in Figure 6, 6 described support frames are respectively the support frame 40 of end face, the support frame 10 of bottom surface and the support frame of four sides, the support frame of described four sides comprises: the first side support frame 20, second side support frame 30, 3rd side support frame 50 and the 4th side support frame 60, first side support frame is positioned at the first side, second side support frame is positioned at the second side, described first side is adjacent and crossing with described second side, first side support frame 20 and second side support frame 30 that intersects vertically,
Wherein, the support frame 10 of described bottom surface, described first side support frame 20 and the push pedal 2 that described second side support frame 30 is respectively equipped with lifting jack 3 and is connected with described lifting jack; As shown in Figure 5, by from described bottom surface, described first side and these three directions, described second side to appear cube pressurization respectively to described rock core, namely from three orthogonal directions pressurizations, simulation triaxial stress.As shown in Figures 1 to 8, the support frame 10 of described bottom surface, described first side support frame 20 is identical with the structure of described second side support frame 30, for the support frame 10 of bottom surface, as shown in Figure 1, the support frame 10 of whole bottom surface is made for casting, the support frame 10 of bottom surface is provided with support 1, be arranged on the lifting jack 3 on support 1 and be connected with lifting jack 3 and be subject to the push pedal 2 that lifting jack 3 promotes, lifting jack 2 is connected with parts such as loading controls by hydraulic line, support 1 can be tabular or the framework with pore space structure, can weight reduction, and be convenient to hydraulic line and be connected with the lifting jack 3 support 1 from the outside of support 1 through support 1.Push pedal 2 directly and rock core to appear the surface contact of cube 70.The huge triaxial stress needed for experiment can be provided to load by lifting jack.In order to reach the needs of loading, the present invention loads 9 lifting jack respectively on each of these three faces, is used for pressurizeing, simulation triaxial stress.The maximum load power of single lifting jack is 320 tons, range 100 millimeters, hydraulic system maximum working pressure (MOP) 63 MPa.
As shown in Figure 6, for the 3rd side support frame 50 and the 4th side support frame 60, and the support frame 40 of end face, their structure is not except having lifting jack and push pedal, all the other structures are all identical, all there is square support 1, each limit of square support 1 is provided with the connection lug 4 of sheet or bulk, the spacing d of adjacent two panels connection lug 4 equals the thickness of single-piece connection lug 4, to make to form grafting by connecting lug 4 between adjacent described each support frame, as shown in Figure 5, 6 support frames are formed and hold rock cores and to appear the space of cube 70.Connect in lug 4 and be provided with connecting hole 5, each connecting hole 5 connected in lug 4 forms straight hole, to wear bearing pin, connects each support frame.As shown in Figure 7 and Figure 8, the support frame 40 of end face is also provided with the mounting hole that sleeve pipe 75 passes, to tests such as sleeve pipe 75 mounting flange 77 and perforations outside the support frame 40 of end face.
Further, the lifting jack 30 of the support frame 10 of described bottom surface, described first side support frame 20 and described second side support frame individually controls pressurization.Under actual geologic condition, stress in the triaxial stress of test specimen or three mutually perpendicular directions is different, the present invention controls the pressurization of the lifting jack on three faces respectively, rock core cube of appearing can be made to accomplish the stress state identical with actual geologic condition.Preferably, the lifting jack that the lifting jack of the support frame of described bottom surface is pressurized to 50Mpa, the lifting jack of described first side support frame is pressurized to 25MPa and described second side support frame is pressurized to 40MPa, this ratio is exactly the stress state of test specimen reality at the scene, now, be loaded into the vertical of surface of test piece and reach 9MPa, 6MPa, 3MPa respectively with horizontal stress, stress reaches desired value, makes experiment consistent with field condition in stress state.
Further, enter hydraulic ejector under in sleeve pipe and realize oriented perforating and pressure break connection is done, by under enter hydraulic ejector and realize oriented perforating at rock core cube of appearing, 6 nozzles installed by described hydraulic ejector, 180 °, phasing degree, 3, every side.This oriented perforating mode is identical with field condition with parameter.
Further, carry out abrasive perforating 10 minutes, close sleeve gate afterwards and carry out rock core and to appear cubical pressure break, pressure break adopts 2000 type Frac units 2 to 6 cover (platform), pressure break discharge capacity 2.0m
3/ min.Pressure break mode is identical with field condition with parameter.
After pressure break terminates, test specimen is taken out from support frame, with the complete dissection to test specimen such as diamond-wire saw, circular handsaw machine and impact pneumatic hammer.
Then survey crack and turn to distance, the rule between the stress difference etc. studying itself and oriented perforating angle, loading.
A specific embodiment is described below
1. test specimen makes
Gather specification 1500 × 1500 × 1500mm cube rock sample as test specimen.Go out the through hole of diameter 240mm, high 1500mm at center Drilling, load 5
1/
2" sleeve pipe, then carry out well cementing of cement.
2. test specimen is installed
First 4 support frames are installed, comprising the support frame of bottom surface and three sides, and on three orthogonal directions, loading fluid cylinder group (totally 27 lifting jack) is installed respectively, then with crane, test specimen is hung on base, remaining two panels support frame is installed afterwards, finally wellhead flange is installed.Pinned connection is used between 6 support frames.As shown in Figure 3, first by the support frame 10 of described bottom surface, described first side support frame 20 and described second side support frame 30 are in place by Fig. 3, lifting jack 3 and push pedal 2 are arranged on the support frame 10 of bottom surface, and then lifting jack and the push pedal of the first side support frame 20 and described second side support frame 30 are installed as shown in Figure 4, then as shown in Figure 5, with crane, rock core cube 70 of appearing is hung in the push pedal of the support frame 10 of bottom surface, then as shown in Figure 6, the support frame 40 of end face is covered on rock core appears cube 70, wherein, pinned connection is adopted to fix between each support frame.
3. pressurizing control system
Connect lifting jack and loading controls, each lifting jack controls separately pressurization, and three faces load 9 lifting jack respectively, is used for pressurizeing, simulation triaxial stress.
4. oriented perforating and fracturing string
Enter hydraulic ejector under in sleeve pipe and realize oriented perforating and pressure break connection work.6 nozzles installed by thrower, 180 °, phasing degree, 3, every side.
5. waterfrac treatment
2000 type Frac units 3 are adopted to overlap, pressure break discharge capacity 2.0m
3/ min carries out abrasive perforating 10 minutes, closes sleeve gate afterwards and carries out pressure break, test specimen moment crack initiation.
6. test specimen cutting
After pressure break terminates, test specimen is taken out from support frame, with the complete dissection to target piece such as diamond-wire saw, circular handsaw machine and impact pneumatic hammer.
7. test observation
Actual measurement crack turns to distance, the rule between the stress difference etc. studying itself and oriented perforating angle, loading.
The foregoing is only the schematic embodiment of the present invention, and be not used to limit scope of the present invention.For each ingredient of the present invention can mutually combine under the condition of not conflicting, any those skilled in the art, equivalent variations done under the prerequisite not departing from design of the present invention and principle and amendment, all should belong to the scope of protection of the invention.
Claims (6)
1. an oriented perforating and fracturing fracture turn to the experimental technique of research, described experimental technique comprises the following steps: A, the rock core adopting the length of side to be more than or equal to 1m cube of appearing makes test specimen, B, then described test specimen is arranged in triaxial stress charger, under the condition that triaxial stress loads, successively oriented perforating and pressure break are carried out to described test specimen, after C, pressure break, dissect described test specimen;
Described steps A comprises: to appear cubical end face central bore at described rock core, then load sleeve pipe, then carry out well cementing of cement;
In described step B, realize oriented perforating by entering hydraulic ejector under in sleeve pipe;
In described step B, carry out abrasive perforating 10 minutes to realize oriented perforating to described test specimen, close sleeve gate afterwards and carry out pressure break to described test specimen, pressure break adopts 2000 type Frac units 2 to 6 covers, pressure break discharge capacity 2.0m
3/ min;
6 nozzles installed by thrower, 180 °, phasing degree, 3, every side.
2. experimental technique as claimed in claim 1, is characterized in that, the described rock core cubical length of side of appearing is 1.5 meters.
3. experimental technique as claimed in claim 1, it is characterized in that, described triaxial stress charger comprises: 6 that are formed by the casting support frames with square support face, pinned connection is adopted to fix between adjacent described support frame, 6 described support frames are formed and surround described rock cores and to appear cubical space, and described rock core cube of appearing is arranged in described space.
4. experimental technique as claimed in claim 3, it is characterized in that, 6 described support frames are respectively the support frame of the support frame of end face, the support frame of bottom surface and four sides, the support frame of described four sides comprises: the first side support frame and the second side support frame, first side support frame is positioned at the first side, second side support frame is positioned at the second side, and described first side is adjacent and crossing with described second side;
The support frame of described bottom surface, described first side support frame and the push pedal of the described test specimen of pushing described second side support frame being respectively equipped with lifting jack and be connected with described lifting jack; By from described bottom surface, described first side and these three directions, described second side load to realize triaxial stress respectively to the cube pressurization of appearing of described rock core.
5. experimental technique as claimed in claim 4, is characterized in that, the lifting jack of the support frame of described bottom surface, described first side support frame and described second side support frame individually controls pressurization.
6. experimental technique as claimed in claim 5, it is characterized in that, in described step B, described triaxial stress is loaded as: the lifting jack that the lifting jack of the support frame of described bottom surface is pressurized to 50Mpa, the lifting jack of described first side support frame is pressurized to 25MPa and described second side support frame is pressurized to 40MPa.
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| CN103776687B (en) * | 2014-01-10 | 2018-05-15 | 天津大学 | Three-dimensional Hopkinson pressure bar steering head device |
| CN108999603B (en) * | 2017-06-06 | 2021-04-30 | 中国石油天然气股份有限公司 | Crack steering performance evaluation method |
| CN112229777B (en) * | 2019-02-26 | 2023-01-20 | 中国石油大学(华东) | Experimental device and method for evaluating plugging effect of temporary plugging ball of perforation blasthole and temporary plugging agent in fracturing crack |
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